1. Field of the Invention
The present invention relates to an image-forming apparatus and more particularly to an image forming apparatus in which image bearing bodies are cooled.
2. Description of the Related Art
A conventional image-forming apparatus such as a color printer, a copying machine, and a facsimile machine is provided with printing mechanisms for forming black, yellow, magenta, and cyan images. One such image forming apparatus is disclosed in Japanese Patent Laid Open No. 2000-19807. Each printing mechanism takes the form of an ID (image drum), which includes an image forming section that forms a toner image of a corresponding color and a transferring unit that transfers the toner image of the corresponding color onto a print medium in registration. A toner cartridge holds toner of a corresponding color and is detachably mounted to the image forming section. The toner is supplied into the image forming section through an opening formed at the bottom of the toner cartridge.
The recording medium is fed from a paper cassette on a sheet-by-sheet basis into a transport path. Then, the recording medium is attracted electrostatically to a transport belt. The transport belt runs through the respective image forming sections in sequence, so that toner images of the respective colors are transferred onto the recording medium in registration with one another. Then, the recording medium leaves the transport belt and subsequently enters a fixing unit where the toner images on the recording medium are fused into a full color permanent image.
With the aforementioned conventional image forming apparatus, poor print quality results from changes in environmental conditions and increased interior temperature of the apparatus due to continuous printing of a large number of pages.
Extremely increased ambient temperatures causes the fluidity of toner in the image forming section to decrease, so that toner become difficult to be transported by a developing roller in a developing unit. As a result, the toner continues to be agitated to agglomerate within the developing unit. This causes degradation of the density, gamma characteristic, and smoothness of continuously changing gradation of halftone images that should be expressed by critical shades of color.